Degradable mesoporous semimetal antimony nanospheres for near-infrared II multimodal theranostics

Abstract

Metallic and semimetallic mesoporous frameworks are of great importance owing to their unique properties and broad applications. However, semimetallic mesoporous structures cannot be obtained by the traditional template-mediated strategies due to the inevitable hydrolytic reaction of semimetal compounds. Therefore, it is yet challenging to fabricate mesoporous semimetal nanostructures, not even mention controlling their pore sizes. Thus, we have developed a facile and robust selective etching route to synthesize monodispersed mesoporous antimony nanospheres (MSbNSs). This is the first report of semimetallic mesoporous structure to the best of our knowledge. The pore sizes of MSbNSs are tunable by carefully controlling the partial oxidation of Sb nuclei and the selective etching of the as-formed Sb2O3. MSbNSs showed a wide absorption from visible to second near-infrared (NIR-II) region. Moreover, PEGylated MSbNSs were degradable and the degradation mechanism was further explained. The NIR-II photothermal performance of MSbNSs was excellent with a high photothermal conversion efficiency of ~44% and intensive NIR-II photoacoustic signal. MSbNSs showed great potential as multifunctional nanomedicines for NIR-II photoacoustic imaging guided synergistic photothermal/chemo therapy in vivo. Our novel selective etching process would contribute to the development of various semimetallic mesoporous structures and efficient multimodal nanoplatforms for theranostics.